How do you build a rocket? Why did airbags deploy on Mars? Who was Hawai'i's astronomer king? Why does "dark matter" matter?

Astronomers are fond of saying they're really just kids who never stopped asking questions, but at the University of Hawai'i Institute for Astronomy's Open House on Sunday, they'll be answering them, too.

Take graduate student Joe Masiero, who'll be conducting the Mars Drop from the second-floor balcony overlooking the courtyard. "This is designed to simulate landing a rover on the surface of Mars, much the way NASA landed Pathfinder, Spirit and Opportunity (in 2004)," Masiero said. "Participants, working in small teams or by themselves, will be given supplies out of which they must construct a device that will safely carry a raw egg from a height of 15 feet to the ground ..."

No word from Masiero on how many dry landings he's had so far.

Mars won't be visible while young engineers work the details of landing an "eggship," but telescopes set up nearby will bring the moon and Venus into view throughout the day as well as search for sunspots. Liz McGrath, another graduate student, will be on hand to advise parents and kids about buying a family telescope and astronomy software.

Kids can learn how to make and launch rockets, and construct comets using dirt and ice mixed with "a secret ingredient." They can "time travel" in the Starlab Planetarium and watch a puppet show that connects Hawaiian culture and modern astronomy.

"We are preparing for our Open House with an enormous enthusiasm," said IFA director Rolf-Peter Kudritzki. "Our faculty, students and staff will be available to help with hands-on experiments, looking through telescopes, showing around the labs or simply talking science and astronomy. For us, it is a unique opportunity to show how fascinating and exciting the modern world of astronomy is."

And high-tech: While landings, launchings and comets are happening in the courtyard, inside the IFA the labs and workshops will be open, Kudritzki said, including the Pan-STARRS lab, where the the biggest digital camera in the world is under construction.

Astronomers like large numbers, and this camera is designed with a light-gathering capacity of 1.4 billion pixels (about 300 times that of an ordinary digital camera), with a shutter opening 18 inches square.

The camera, destined for the observatory on Haleakala at the end of the year, will survey the sky for dangerous asteroids in orbits that threaten Earth.

"It's about what these objects could do to Earth and what we can do to them," said asteroid hunter Robert Jedicke, whose talk on "Killer Asteroids" will be among the hot topics presented in the lecture theater from noon.

Other talks include findings from the Deep Impact mission July 4, 2005, when scientists crashed a probe into comet Tempel 1, 83 million miles from Earth, as well as a look at the mysterious "Dark Matter and Dark Energy" — what we don't know about 95 percent of the universe.

Solar astronomer Shadia Habbal will show photos and talk about the IFA expedition to Libya to view last month's solar eclipse.

Deep in the Sahara Desert hundreds of miles from the Chad border, Habbal and a team of IFA astronomers set up camp for six days to measure, among other things, the temperature of the outer corona of the sun visible only during a solar eclipse.

"Despite the logistics of taking a ton of equipment from Manoa to the Sahara, the remote location and transportation via military planes, everything went extremely smoothly, and we came back with surprising results," Habbal said, "... with much credit going to the Libyans for their assistance."

In 1880, King David Kalakaua visited the Lick Observatory in San Jose, Calif., which inspired a lifetime enthusiasm for astronomy and brought about the first permanent telescope in Hawai'i, a 5-inch refracting telescope installed in the dome above Pauahi Hall at Punahou School in 1884. Today, Kudritzki said, Hawai'i leads the world in astronomy.

"Visitors will see stunning pictures of the most recent detections made with the giant telescopes on Mauna Kea and Haleakala, and learn about revolutionary future telescope projects at the Institute," Kudritzki said.

Open House is their "mission possible," he said: "We want to share the enthusiasm about our work and inspire the community and most importantly to get the message out to all the kids that science is exciting and fun. Maybe we can plant a few seeds to create the scientists of tomorrow."

Reach Chris Oliver at coliver@honoluluadvertiser.com.